1. Field of the Invention
This invention relates generally to pulse sensing feedback control systems, and more particularly to a pulse sensing feedback control system with features adapted for remote operator control of a distant system by utilizing a pressure sensitive control device that detects and counts pulses produced manually in liquid or gas flowing through a pipe.
2. Description of Related Art
The following art defines the present state of this field:
Price et al., U.S. Pat. No. 3,716,949 describes a feed rate and positioning control system for a machine tool which utilizes an electrohydraulic pulse motor to move a grinding wheel support at preselected rates and for predetermined distances during a grinding operation. A control counter is arranged, via rate selecting switches, to select pulses of various predetermined pulse repetition rates for controlling the rates at which the electrohydraulic pulse motor moves during a grinding operation. End point selecting switches and comparators are provided for determining the distances moved by the support during a grinding operation to signal the control counter to change rates or to start a swell period. Swell selecting switches, responsive to the control counter, are provided to establish the duration of swell periods between application of selected rates and to signal the control counter at the end of each swell period, including a spark out period at the end of the grinding operation.
Milberger et al., U.S. Pat. No, 4,185,541 describes a method and apparatus for hydraulically controlling subsea well equipment, such as valve operators, connectors, and other hydraulically actuated devices, with a significantly reduced number of hydraulic pressure source lines from the surface to the subsea location of said well equipment. The apparatus includes a multi-mode subsea switching valve having a plurality of module-like sections, each section having an inlet port, a vent port and a plurality of outlet ports. When installed, this valve preferably is located near the subsea well, and a source of hydraulic pressure and a plurality of hydraulic switches, all located on a surface vessel or other surface facility, are connected to the valve's inlet ports by means of a relatively small number of hydraulic pressure source lines. A relatively large number of hydraulic outlet lines interconnect the valve's outlet ports and the subsea well equipment so that in each of its functional modes the valve directs fluid pressure to a different set of subsea devices. The valve is switched from one mode to another by a pulse of hydraulic pressure exerted on an operator apparatus that is connected to the valve's flow control element, and these modes are changed in a manner such that the position of the valve's flow control element is always known.
Snead, U.S. Pat. No. 4,230,196 describes a loader which includes a lift arm assembly, raised by hydraulic lift cylinders and carrying a load bucket. Alignment members mounted respectively on the loader frame and lift arm assembly, and visible to the loader operator, identify the weigh position of the lift arm assembly. A pressure to voltage transducer is mounted on one lift cylinder, and is connected in a bridge circuit producing a DC voltage output. The bridge circuit output signal, proportional to the bucket load, is fed to an amplifier, whose output is passed to an analog-to-frequency converter producing pulses at a frequency proportional to the bucket load. An electronic clock allows the converter output pulses to pass through an AND gate to a bucket counter which displays the bucket load, and is automatically reset to zero. The converter pulses are passed to an accumulator counter through a second AND gate. The accumulator counter accumulates the weight of several bucket loads which are loaded onto a transport vehicle; and is reset manually after the vehicle is loaded.
Rajagapal et al., U.S. Pat. No. 4,343,365 describes a control system for a tractor hydraulical power lift system having an electrohydraulic actuator coupled to a main hydraulic valve, comprising a feedback electronic control circuit including a circuit for mathematically combining a plurality of transducer generated signals into a command signal. The command signal comprises the output signal of a first differential summing device receiving a first input signal for a control handle transducer from which is subtracted a second input signal produced as the output of a signal mixer that combines input signals from a rockshaft transducer, a draft selector transducer and a draft load transducer. The command signal and a signal from a transducer coupled to the electrohydraulic actuator are fed into a differential summing device that has as its output an error signal representing the actual and desired positions of an implement to be positioned by the power lift system. The control circuit includes a sample-and-hold unit adapted to receive the error signal. Clock logic transmits the error signal at predetermined times as determined by a sampling frequency clock from the sample-and-hold unit to the electrohydraulic actuator.
Zettergren, U.S. Pat. No. 4,360,807 describes a device for remote control of hydraulic or pneumatic machine tools, comprising a selector valve for different hydraulic functions provided with a number of spring-centered slides and two electrohydraulic or -pneumatic converters connected to each slide, and comprising a control unit capable by electric impulses to transfer orders via a cable to a receiver unit capable to control the converters. According to the invention, the control unit comprises a ring counter, which is controlled by an oscillator and capable to emit in turn a scanning signal to each of a number of transducers, which are manually actuated by levers, each transducer being capable during the duration of the scanning signal to convert the direction and deflection from a centered zero position of the associated lever into two signals, one of which corresponds to said direction and one to said deflection. An encoder is provided to allot an address to the output signals. The receiver unit comprises a decoder capable to emit a decoded signal to a signal converting circuit thereby addressed where two such circuits are corresponded by a transducer. The circuits are connected each to an amplifier, each of which is capable to control one of said converters.
Salzgeber, U.S. Pat. No. 4,476,837 describes a fuel pump timing system having a hydraulic pressure transducer mounted for sensing a reaction hydraulic pulse to each fuel injection pressure pulse, a stepper motor for adjusting the fuel injection pump timing, engine sensors for sensing an engine reference position and certain engine operation data and a microprocessor connected to the transducer and engine sensors and operable for calculating the optimum and actual angles of fuel injection and for controlling the stepper motor to adjust the fuel injection pump timing in accordance with the difference between the optimum and actual angles of fuel injection.
Lucas et al., U.S. Pat. No. 4,721,028 describes a control system for controlling the movement of the slide of a hydraulic press of the type having a main cylinder containing a piston mounting the slide. The control system compriscs an electronic processor, a pressure transducer to measure the pressure of hydraulic fluid applied to the piston to move the slide downwardly, a position encoder coupled to the slide to determine the vertical position of the slide, and a hydraulic circuit to supply hydraulic fluid under pressure to the cylinder to move the piston and slide upwardly and downwardly. The hydraulic circuit comprises a plurality of cartridge valves having controls actuable by outputs from the processor. The processor is capable of handling inputs, including inputs from the pressure transducer and position encoder, and outputs to control the hydraulic circuit to shift the slide upwardly and downwardly at different preselected speeds, to reverse downward travel of the slide at a preselected point based on either slide position or tonnage applied by the slide to a workpiece, and to adaptively optimize decompression of the hydraulic fluid in the hydraulic system at the end of downward movement of the slide.
Kipfelsberger, U.S. Pat. No. 4,887,499 describes a power screwdriver with torque limiter, with a drive unit and a secondary transmission, with an output shaft for the attachment of a keyed bit. According to the invention the drive unit is a pneumatic motor with a compressed-air intake and a compressed-air outlet, whereby the differential pressure between the compressed-air intake and the compressed-air outlet (measuring circuits) taken as the measure of the torque produced by the power screwdriver. The differential pressure is measured in a differential pressure measuring device and the measure signal is transmitted to a control unit. The control unit contains a comparator unit which compares the measured differential pressure signal with a set value of differential pressure (adjusting potentiometer) and transmits a switching signal to a switch unit (solenoid valve) to switch off the power screwdriver when the compared values become equal. In this manner a simple calculation of torque is achieved by means of a differential pressure measurement in combination with a simple switch-off possibility. In further embodiments the rotational speed of the pneumatic motor is used additionally in the determination of torque.
Ohkubo et al., U.S. Pat. No. 5,113,949 describes a tightening control apparatus for a torque wrench including a pressure detecting device for detecting an admission pressure supplied to a torque wrench. A pressure change detecting device determines a change in pressure detected by the pressure detecting device. A striking signal output device outputs a striking signal when the change reaches a reference value.
Ohta et al., U.S. Pat. No. 5,421,240 describes torque control of high accuracy by detecting the oil pressure at the time of the generation of a pulse which forms the basis of the generated torque for a torque wrench and using the data thus obtained the effect torque control. Oil pressure pulses generated in a pulse generating mechanism by the rotation of an air motor are transmitted to a hydraulic cylinder by a piston, a rod and a piston. In addition, a pressure sensor installed in the hydraulic cylinder detects the oil pressure pulses and its signal is used to switch a switching valve, whereupon a stopping switching valve and a stopping differential pressure valve are successively switched, stopping the feeding of air to the air motor while cutting of the passage of electric current from a battery to an electric control circuit.
Panoushek et al., U.S. Pat. No. 5,455,769 describes a control system for controlling the height of a harvesting head on a combine is disclosed herein. The control system includes operator controlled signal generators which permit an operator to independently set the maximum velocity at which the harvesting head is raised and lowered. The signal generators are connected to the system controller which controls the operation of a hydraulic valve which controls hydraulic lift cylinders which raise and lower the harvesting head. The hydraulic valve is controlled with a pulse-width modulated signal. The width of the pulse is related to the direction the head is being moved (raised or lowered), and the maximum speed at which the head is to be moved. To reduce jerking upon initiation of head movement and termination of head movement, the controller determines acceleration and deceleration rates for head movement initiation and termination. The acceleration and deceleration determinations are based upon the signals produced by the signal generators.
It is often desired that control of systems, machines or functions of machines can be effected from a distance, so that an operator can remotely initiate changes in operation of a system or a machine. The prior art includes various apparatuses which use hydraulic pulse sensing for valve control, system feedback, pressure and motor control of the hydraulic system producing the pulse, including an electrohydraulic pulse produced in a controlled hydraulic system to activate response functions in the same hydraulic system. However the prior art does not teach that an operator can use hydraulic pulse sensing to remotely control a separate system, where the function of the remote system is not directly related to the function of the hydraulic system itself. The present invention fulfills these needs and provides further related advantages as described in the following summary.